Electroanatomic Mapping and Ablation
All procedures were performed under general anesthesia. Antiarrhythmic
agents, if present, were not discontinued. Patients maintained
anticoagulant treatment (acenocumarol with INR from 2 to 3.5, or direct
oral anticoagulants, with last dose the night before the procedure).
After vascular access was obtained, a double transseptal puncture was
performed and intravenous heparin was administered to maintain an
activated clotting time of more than 300 seconds. Thereafter, two long
sheaths (1 SL0 sheath and 1 Agilis sheath; St. Jude Medical, Inc., St.
Paul, MN) were inserted into the left atrium. The following catheters
were used: a decapolar catheter WEBSTER® CS Catheter (Biosense Webster)
placed in the coronary sinus as a reference (6Fr), a Pentaray® catheter
(Biosense Webster) with F curve 2-6-2 mm spacing between electrodes
(7Fr) as a high density mapping catheter (10 pairs of electrodes) and a
SmartTouch SF with an F curve as an irrigated-tip contact force ablation
catheter (7.5Fr).
Three-dimensional geometry of the left atrium and 4 pulmonary veins
(PVs) was reconstructed with the use of Carto3 mapping system (Biosense
Webster, Inc.). To ensure that mapping catheter is in contact with the
tissue, CARTO system features the TPI or Tissue Proximity Indicator,
which performs an impedance matrix. When it contacts with the cardiac
wall, the catheter has less ion-charged blood, so impedance rises. To
carry out the automatic acquisition of points, a series of filters were
included. Those used for the acquisition of these maps are the
following: Cicle Lenght Filtering (not in AF), Local Activation Time
Stability (not in AF), Position Stability, Density and Respiration
Gating.
We recorded multiple bipolar signals (filter setting: 30– 300 Hz) from
the Pentaray catheter, first in AF and later in SR after electrical
cardioversion. Operators mapped carefully to ensure that the entire left
atrium anatomy was represented in both the SR and the AF maps. All
points within the pulmonary veins and LA appendage were excluded. After
both electroanatomical maps were completed, ablation was performed as
usual in our center: ipsilateral PV isolation in pairs, with entrance
and exit block as the electrophysiological endpoint. In some cases,
ablation could also include lines of ablation, at operator’s discretion.
All procedures were performed by two expert operators.